No abstract available.
Polymers*

No abstract available.
Polymers*

PURPOSE: Polymer infiltrated ceramic network (PICN) materials, also called hybrid ceramics, are new materials in dental market. The manufacturer of the PICN material VITA Enamic suggests 3 different finishing procedures for this new material. In the present study, surface roughness and color differences caused from different finishing procedures of VITA Enamic were investigated. MATERIALS AND METHODS: 120 specimens were prepared in dimensions 2 x 10 x 12 mm from VITA Enamic hybrid ceramic blocks with 'high translucency' and 'translucency 2M2' shades. The specimens were divided into 8 groups. For each group, different finishing procedures suggested by the manufacturer were performed. Surface roughness values were determined by a tactile portable profilometer. Color changes were evaluated using a clinical spectrophotometer. The data were analyzed using one-way ANOVA and Tukey's post-hoc comparison. The significance level was set at alpha=0.05. RESULTS: The roughest surfaces were observed in Glaze Groups. Their surface roughness values were similar to that of the control group. Clinical Kit and Technical Kit groups did not show a statistically significant difference regarding surface roughness (P>.05). The largest color difference regarding DeltaE00 was observed in Clinical Kit finishing groups. There were also statistically significant color changes between the groups (P<.05). However, all the groups showed clinically acceptable color change (DeltaE(00)<2.25) except Clinical Kit Groups (DeltaE(00)>2.25). CONCLUSION: Within the limitations of the present study, it may be suggested that finishing the VITA Enamic restorations by Technical Kit instead of Glaze and Clinical Kit gives better clinical performance in regard to surface roughness and shade matching.
Ceramics* ; Polymers*

The study was carried out on 48 workers producing polymer-composite material for over 2 years. The results showed that: although the exposure time is not so long, the polymer-composite material producing has influenced badly to workers' health such as: headache, fatigue... Workers have to be off more because of illness. There are functional changes of central nervous system such as: longer simple reaction time, impairment of short-term memory; decrease of concentration; decrease of electrical activeness of cerebral cortex and sleepy disorder.
Health ; Polymers

This study aimed to determine whether the curing times of Xtra Power and High Power modes of high-power light emitting diode (LED) curing light are sufficient for polymerization of resin sealants. The specimens were prepared and their microhardness values were measured and compared with those of specimens polymerized under conventional LED curing light.The filled sealant polymerized for 8 seconds in the High Power mode and for 3 seconds in the Xtra Power mode showed significantly lower microhardness than the control specimen (p = 0.000). The unfilled sealant polymerized for 8, 12 seconds in the High Power mode and for 6 seconds in the Xtra Power mode showed significantly lower microhardness than the control specimen (p = 0.000).The results of this study suggest that the short curing time with the Xtra Power and High Power modes of highpower LED curing light are not sufficient for adequate polymerization of sealants under specific conditions, taking into account the curing times and the type of sealant.
Polymerization ; Polymers

This study evaluated the effectiveness of the light emitting diode(LED) units for composite curing. To compare its effectiveness with conventional quartz tungsten halogen (QTH) light curing unit, the microhardness of 2mm composite, Z250, which had been light cured by the LEDs (Ultralume LED2, FreeLight, Developing product D1) or QTH (XL 3000) were compared on the upper and lower surface. One way ANOVA with Tukey and Paired t-test was used at 95% levels of confidence. In addition, the amount of linear polymerization shrinkage was compared between composites which were light cured by QTH or LEDs using a custom-made linometer in 10s and 60s of light curing, and the amount of linear polymerization shrinkage was compared by one way ANOVA with Tukey. The amount of polymerization shrinkage at 10s was XL3000 > Ultralume 2, 40, 60> FreeLight, D1 (P<0.05) The amount of polymerization shrinkage at 60s was XL3000 > Ultralume 2, 60> Ultralume 2,40> FreeLight, D1 (P<0.05) It was concluded that the LEDs produced lower polymerization shrinkage in 10s and 60s compared with QTH unit. In addition, the microhardness of samples which had been cured with LEDs was lower on the lower surfaces than the upper surfaces whereas there was no difference in QTH cured samples.
Polymerization* ; Polymers* ; Quartz ; Tungsten

The purpose of present study was to evaluate the polymerization shrinkage stress and amount of linear shrinkage of composites and compomers for posterior restoration. For this purpose, linear polymerization shrinkage and polymerization stress were measured. For linear polymerization shrinklage and polymerization stress measurement, custom made Linometer (R&B, Daejon, Korea) and Stress measuring machine was used (R&B, Daejon, Korea). Compositers and compomers were evaluated; Dyract AP (Dentsply Detrey, Gumbh. German) Z100 (3M Dental Products, St. Paul, USA) Surefil (Dentsply Caulk, Milford, USA) Pyramid(Bisco, Schaumburg, USA) Synergy Compact (Coltene, Altstatten, Switzerland), Heliomolar (Vivadent/Ivoclar, Liechtenstein), and Compoglass (Vivadent Ivoclar/Liechtenstein) were used. 15 measurements were made for each material. Linear polymerization shrinkage or polymerization stress for each material was compared with one way ANOVA with Tukey at 95% levels of confidence. For linear shrinkage; Heliomolar, Surefil Compomers* ; Daejeon ; Polymerization* ; Polymers*

Although many prosthetic materials exist for fabrication of implant-supported telescopic overdentures, available materials have not been thoroughly evaluated from a functional standpoint. This case report describes the use of polyaryletherketone (PAEK) based polymer for an implant-supported telescopic overdenture, a seldom used material in dentistry. This material is lighter than traditional materials, can accommodate changes in retentive forces, and is an easily retrievable by CAD/CAM fabrication. This case highlights the possibility of using new polymer materials for implant-supported telescopic overdentures.
Dentistry ; Denture, Overlay* ; Polymers*

OBJECTIVES: This study investigated the optimal combination of 3-component photoinitiation system, consisting of CQ, p-octyloxy-phenyl-phenyl iodonium hexafluoroantimonate (OPPI), and 2-dimethylaminoethyl methacrylate (DMAEMA) to increase the degree of conversion of resin monomers, and analyze the effect of the ratio of the photoinitiator to the co-initiator. MATERIALS AND METHODS: Each photoinitiators (CQ and OPP) and co-initiator (DMAEMA) were mixed in three levels with 0.2 wt.% (low concentration, L), 1.0 wt.% (medium concentration, M), and 2.0 wt.% (high concentration, H). A total of nine groups using the Taguchi method were tested according to the following proportion of components in the photoinitiator system: LLL, LMM, LHH, MLM, MMH, MHL, HLH, HML, HHM. Each monomer was polymerized using a quartz-tungsten-halogen curing unit (Demetron 400, USA) for 5, 20, 40, 60, 300 sec and the degree of conversion (DC) was determined at each exposure time using FTIR. RESULTS: Significant differences were found for DC values in groups. MMH group and HHM group exhibited greater initial DC than the others. No significant difference was found with the ratio of the photoinitiators (CQ, OPPI) to the co-initiator (DMAEMA). The concentrations of CQ didn't affect the DC values, but those of OPPI did strongly. CONCLUSIONS: MMH and HHM groups seem to be best ones to get increased DC. MMH group is indicated for bright, translucent color and HHM group is good for dark, opaque colored-resin.
Ethylamines ; Methacrylates ; Polymers ; Terpenes

The purpose of this study was to compare the effect of exponential curing method with conventional curing and soft start curing method on polymerization shrinkage of composite resins. Three brands of composite resins (Synergy Duo Shade, Z250, Filtek Supreme) and three brands of light curing units (Spectrum 800, Elipar Highlight, Elipar Trilight) were used. 40 seconds curing time was given. The shrinkage was measured using linometer for 90 seconds. The effect of time on polymerization shrinkage was analysed by one-way ANOVA and the effect of curing modes and materials on polymerization shrinkage at the time of 90s were analysed by two-way ANOVA. The shrinkage ratios at the time of 20s to 90s were taken and analysed the same way. The results were as follows: 1. All the groups except Supreme shrank almost within 20s. Supreme cured by soft start and exponential curing had no further shrinkage after 30s (p < 0.05). 2. Statistical analysis revealed that polymerization shrinkage varied among materials (p = 0.000) and curing modes (p = 0.003). There was no significant interaction between material and curing mode. 3. The groups cured by exponential curing showed the statistically lower polymerization shrinkage at 90s than the groups cured by conventional curing and soft start curing (p < 0.05). 4. The initial shrinkage ratios of soft start and exponential curing were statistically lower than conventional curing (p < 0.05). From this study, the use of low initial light intensities may reduce the polymerization rate and, as a result, reduce the stress of polymerization shrinkage.
Composite Resins* ; Polymerization* ; Polymers*